(a) Field of the Invention
The present invention relates to a DOHC diesel engine, and in particular, to a cylinder head structure of the DOHC engine for providing improved engine maintainability.
(b) Description of the Related Art
Diesel engines are designed to operate on either two or four stroke-cycles. In a typical four-stroke engine, intake and exhaust valves are located in the cylinder head. Often, dual valve arrangements with two intake and two exhaust valves per cylinder, are employed.
A DOHC (dual overhead cam) engine with four valves per cylinder has two camshafts per cylinder head. Generally, one camshaft operates intake valves, the other operates exhaust valves. The intake and exhaust ports are commonly fashioned in a tandem, parallel, or twisted arrangement, and a fuel injector for each combustion chamber is provided for high-pressure fuel injection.
FIG. 1 is a cross-sectional view showing a cylinder head wherein the intake and exhaust ports are arranged in tandem. As shown in FIG. 1, the valves are parallel such that there are some advantages in that dead combustion chamber volume is reduced, the valve train can be compact, swirl is encouraged, and the mounting of glow plugs is facilitated. There are also shortcomings in that it is difficult to install and remove fuel injectors, and cooling efficiency is reduced.
FIG. 2 is a cross-sectional view showing a cylinder head wherein the intake and exhaust ports are arranged in parallel. As shown in FIG. 2, the valves are arranged to be non-parallel such that the space for installing and removing the fuel injector is increased. However, the non-parallel configuration of the valves causes the dead volume of the combustion chamber to increase and the valve train to be complicated. Furthermore, this parallel port arrangement increases intake resistance.
FIG. 3 shows a cylinder head wherein the intake and exhaust ports are arranged in a twisted fashion. The twisted port arrangement makes it easier for allows the intake ports to develop swirl, and it includes all the advantages of the tandem arrangement. However, the twisted port arrangement also has shortcomings in that it is difficult to install and remove the fuel injectors on the cylinder head.
To increase engine performance, there are many advantages to adapting the twisted port arrangement, such as increasing swirl efficiency and smoothing the intake and exhaust flow. It also more easily secures space for mounting the glow plug.
In addition, to adapt a common-rail type fuel injection system for reducing fuel injection pressure and noise, the fuel injector should be arranged in such a way that it is affixed on the valve cover.
However, in the prior art cylinder head, shown in FIG. 1 an injector clamp 17 is pre-mounted on the cylinder head.
The present invention has been made in an effort to solve the above problems of the prior art.
It is an object of the present invention to provide a DOHC diesel engine cylinder head that makes maintainability of the engine easy by modifying the cylinder head and valve structure.
To achieve the above object, a DOHC diesel engine cylinder head comprises a plurality of combustion chamber head sections having the same configuration, two camshafts rotationally mounted over the combustion chamber head sections, each having cam lobes for activating intake and exhaust valves, synchronizing means for driving the camshafts, the synchronizing means being connected to the camshafts, a camshaft carrier mounted on a top surface of the cylinder head for supporting the camshafts, and a valve cover for covering the cylinder head.